LGBT activists in Australia are worried they will lose an important ally in Parliament after a married politician, Mark Brindal, admitted to having an affair with a 24-year-old man earlier this year.

The Australian daily newspaper reported Mark Brindal, a lawmaker from South Australia, was the subject of a blackmail attempt by the 24-year-old's foster father in June. Police are now investigating.

After news of the affair became public, Brindal announced Tuesday he would not stand as a Liberal candidate in state elections next March.

"I have decided to withdraw as the Liberal candidate for Adelaide," Brindal announced on his Web site. "The media frenzy of the last few days in relation to my actions has caused an impact on my family and my party, which I deeply regret."

"Following consultation with my wife and my close political colleagues, I believe that this decision reflects particularly the needs of my family and the interests of the Liberal Party as it prepares for the next election," he added.

"I have been honest and up front in respect to my actions and involvement. However inappropriate those actions were, the matter remains deeply personal and private, and needs to be worked through with those I love," Brindal concluded.

However, the politician told reporters he would not have regretted the affair if it had not been made public. He accused "homophobic" members of the Liberal party of pushing for his departure.

"Some members in the Liberal Party pushed me by exhibiting their extraordinary 1950s Neanderthal intelligence," Brindal told the Herald Sun.

Brindal threatened that if he goes, he will take other politicians with him. "If my personal life has been fair game, I really don't see why anybody else's shouldn't be," he said. "That includes serial womanizing, drinking, gambling, debts -- many, many things."

His departure from the Liberal ticket is a setback for South Australia's gay law reform process, according to Matthew Loader, a spokesman for South Australian gay rights lobby group Let's Get Equal.

"In very simple terms, South Australia will lose a very good parliamentary advocate, someone who has been consistently strong [on] and committed to gay rights legislation," Loader told the Sydney Star Observer.

Brindal's resignation comes nearly one year after a similar resignation by a governor in the United States who admitted he had an extramarital affair with a man. James McGreevey, the former governor of New Jersey, made his announcement on Aug. 12, 2004, during which he also came out as a "gay American."